How's a metal roof compare to a shingle roof in a cold weather climate?
the cost of a new metal roof, they say, is 3 times as much as shingles, but, can last twice as long with less effort taking down the old material when it needs to be replaced, so... ive been a fan on metal roofing but in my particular situation i am considering buying a home that already has metal roofing and would like to know as much about efficiency bc it is a log home in the first place (log homes are inefficient against cold climates)
Can an existing home be made bushfire-proof (or more resilient to fire)?
As said, keep anything combustible well away from the house. Remove any plant that is dead. Dont allow trees to overhang the house. Dont use mulche or wood chips on the garden. For the house, ensure there is no combustible way of fire getting into the house. Make sure eaves do not allow embers to fly in, and are not of a material that will burn. All external paint should of a fire-proof variety. Windows should be treated to repel heat or be covered with fireproof shutters. - When bush fires take out suburban streets, often the fire gets into houses because the heat of the fire next door shatters the windows and then embers blow in onto curtains and carpets etc. Especially when large bushes are right next to windows. Gutters should have a stopper fitted at the top of each downpipe, so that the roof can be sprayed with water so that water will sit in the gutters. If you live in a bush fire prone area, you should have water tanks at the front and back of your house, with their own pumps and hoses, in addition to mains water hoses. If the mains water fails, you have backup. Also have shovels and loose damp sand on hand - damp sand or earth is often better at putting out some types of fire. Many homes are saved because the owner stayed to fight it and was prepared.
If the atom contains 99.9% of nothing, why aren’t we just a tiny bit transparent?
As stated in previous answers, transparency (or transmissivity) depends on the wavelength of the incident light. I’d like to add a tiny remark.We are quite transparent at certain wavelengths…Extremely high energy photons associated to insanely short wavelengths will go right through you, and sometimes interact, and indeed destroy, base pairs that form your DNA.You heard of them. Gamma rays. And although a thin wall will shield you from visible photons, a good proportion of gamma rays will go through it, and in turn through you or get absorbed by you. So if there’s a nuclear detonation close to you, even though hiding behind a wall may save you from blast injury, you may still get cooked enough for Gordon Ramsay to consider you well done.Oh and also, it’s quite hard to define a “vacuum” in the “space” that would separate electrons from the nucleus.You’re better off thinking that what surrounds a nucleus is a mess, of delocalized electrons, and what carries their interaction with the nucleus (i.e. photons and gauge bosons).It’s more like a “soup”. And some incoming photons from “the outside” will just pass through, or get absorbed and re-emitted by electrons, or get absorbed and kick one or more electrons away from the nucleus’ influence (ionization, which is why high energy radiation damages your DNA).
Can dried up gasoline catch on fire?
Pure gasoline evaporates completely from an impermeable surface, leaving nothing behind to burn. BUT:Gasoline you put in your car is not pure. It has additives and impurities, heavier “oily” petrocarbons and solids which are also flammable (but MUCH less flammable than gasoline - very hard to light on fire - and requiring a substantial volume to sustain a flame, which is unlikely to ever be the case in a residual stain).Impermeable surfaces are rare. Gasoline will “soak in” to almost anything other than glass or metal, thereby slowing its evaporation, staining surfaces like concrete, or even combining chemically with fabrics, paint, plastics or rubber. In general, even a permeable surface that has had time to “dry” will be essentially no more flammable than it was before the gasoline got on it. Fabrics and wood, being extremely porous, can trap more of the volatile compounds and will combust more readily after soaked in gas.One answer here states that water will wash away residual gasoline stains. Untrue. Water and oily petrocarbons are immiscible. They cannot mix. To wash away gas stains requires a detergent to reduce the surface tension of the water and bind the oil to it, and preferably pressure or scrubbing to break up the long oil molecules and allow water to wash them away.
Why are houses in the USA made from wood and brick, whereas houses in other developed countries are made from concrete or tin? Which is more durable and less costly? Can plumbing be hidden inside the walls in a concrete house, as in a wood house?
Pretty much everywhere in the world houses and buildings are built with CMU blocks, because they are inexpensive and easy to work with.My understanding is that the US builders keep building with wood because it is the most inexpensive local construction material and US consumers are obviously not worried about durability. They also probably lack the manpower and knowledge basis for this type of work so they stick with what they know better.In Europe, people usually expect their house to last several generations, whereas the oldest homes in the US must be 120 years old; maybe there is something about that.Houses in the US are tore down and rebuilt at a much higher pace than in old Europe.In the long run, concrete homes are very likely more economical; they last much longer, they do not have mold or termite issues, concrete blocks do not crack or twist like wood does. They hold off much better against elements.Still, they offer great flexibility; you can easily delete and move the walls as long as they are not bearing the roof.On top of that, CMU walls have higher fire and weather insulation properties than a typical wood frame wall. A hollow CMU block has a fire rating of 2 hours upgraded to 4 hours if the cells are grouted or filled with other filling materials(which is the case most of the time)A typical wood frame wall made of 2x6 with 2x 1/2 drywall board and fiberglass wool insulation would likely fail in 30 minutes, unless built with modern 5/8 commercial grade X type gypsum boards; but still the wall would only hold 1 hour against 4 hours with a CMU wall.The vast majority of houses in the mediterranean do not have air conditionning even though the temperatures often reach over 100 degrees. Walls are typically made of stucco over hollow or grouted (filled) CMU blocks and clay tiles roofs.People usually keep the windows and doors closed during the hottest hours of the day and open at night so the house remain cold without using ventilation or AC, which proves the effectiveness of such constructions against extreme temperatures
What will happen if you put a magnet on fire?
You don't have to set it on fire, all you need is heat it up. At some point, it will reach a temperature called the "Curie temperature" (different for each type of material). Heat is stored in objects as vibration of the molecules. Magnets are what they are because "domains" of molecules have their tiny portion of magnetism aligned with each other. If you have a large number of domains aligned in the same direction, you have a magnet. --- On ships, the magnetic compass is in a binnacle, with "correcting spheres" made of pure iron (not steel). These are the two balls (one painted red, the other painted green): http://upload.wikimedia.org/wikipedia/co... For the compass to work well, the spheres must have NO permanent magnetism (the domains MUST be randomized). On older steam ships that did not have sealed heating system, when we noted that the spheres had permanent magnetism, we would put them in the fire box of the boiler and heat them above their Curie temperature. Of course, we would have to repaint them. (yes, I am that old) Otherwise, we would roll them violently on the deck (strong mechanical shocks will also disrupt the alignment of domains). When you heat it up, the vibration breaks down the alignment. Enough heat = enough vibration = all the domains are randomized. The temperature at which this happens is called the Curie temperature. Most magnets are metal, therefore difficult to set on fire. Still, they can be heated. However, many magnets are made by suspending magnetized iron filings in a plastic that is liquid at low temperature (below iron's Curie temperature). The liquid plastic is allowed to solidify while in a magnetic field (the field will align the iron filings giving you well-aligned domains). If you can find this type of magnet (most modern powerful, tiny magnets are of this type), then setting the plastic on fire could generate heat beyond the iron's Curie point. But it will also certainly generate toxic fumes (because of the plastic). .
Could I use cinder blocks to construct a fire pit?
We have a ton of cinderblocks in our backyard so I was wondering if my husband put them in a box or circle shape, could we do a fire in there? We know how to make fires, but could cinderblocks be good to make a firepit?